Scaled image anti alias

Hey guys.

Ive searched for the problem i have here on these forums but without result. Maybe it has already been discussed before, if so, please reply a link.

Anyways, my problem is, when scaling an image down (lets say 800×600) dynamicly to like 50 percent its getting very edgy. Is there a posibilaty to like anti alias the pic so it looks smooth?

http://www.laurengreenfield.com/index.php?p=9R2AJPO2

In here the pictures dont get edgy because they cant scale down that much because of the table “boundries”. but it doesnt seem the picture gets edgy/blurry when you scale it bigger.

So does one of you know if its possible to make a picture anti aliased when scaling down or is that just impossible?